It is desirable to have watercrafts to remain afloat even when the open hull becomes filled of water. To make this possible discrete floatation chambers have been employed in watercraft for many years. Thus, in the event that the seal of one chamber is compromised and the buoyant effect of that chamber is lost, the other chambers will still have a buoyant effect so that the watercraft will remain afloat.
Due to the safety problems of punctured chambers the U.S. Coast Guard has implemented rigorous standards with which the boats under their jurisdiction must comply. One such regulation is the mandatory use of foam in the chambers to reduce the amount of water the chamber would take on in the event the chamber wall is punctured. There are many problems with foam injected chambers. First, it is very costly to inject foam into the chamber; the foam must be distributed evenly and the injection equipment is expensive to purchase and maintain. Secondly, If the foam filled chamber is punctured, repair of the chamber is difficult to impossible. It is somewhat difficult to remove the water that is soaked into the foam. Further, the aluminum wall that defines the chamber must be welded to recreate a sealed chamber and the heat from the welding process will melt the foam, creating noxious gas and leaving a portion of combusted foam no longer of use for floatation.
Another aspect of the design and manufacture of floatation boats is the construction of chambers has traditionally been accomplished by rolling sheets of aluminum to form a curved wall to define the chambers. There are numerous problems with the rolling process that results in variations in the shape and dimensions in the chamber walls. This lack of consistency makes the use of efficient manufacturing techniques difficult or in some instances impossible.
Another method of creating chamber walls is to extrude the aluminum through a mold to a preferred shape. This process is very expensive and can weaken the metal.
Yet another aspect related to the larger boats which generally have an internal combustion engine to power the prop, the fuel tank must reside in a safe place while still having a convenient access to the tank. The inlet port to refuel the tank has traditionally been in the back of the water vessels near the engine. Often times when a boat is in the water, the rear of a boat is lower than the front, because there is generally more load to the rear of the center of buoyancy of the water vessel. This position of the boat causes the gas to shift to the rear of the tank, which increases the hydrostatic pressure for a refueling inlet port located in the rear of the boat. This increase in pressure makes refueling more difficult